The invention relates to a curved assembly line and/or conveyor belt, in particular for the assembly and transport of motor vehicles or motor vehicle parts in production, which is formed by carrying elements which are mounted in an articulated manner with respect to one another and engage positively one into the other and which have in each case an upper platform and a lower carrying frame and the end faces of which are convexly and concavely curved in the form of an arc of a circle with approximately identical radii of curvature, so that in each case a convex and a concave recess of two adjacent carrying elements form, bearing positively one against the other, a continuous conveyor belt transition both in curved sections and on a straight line.
Assembly lines and/or conveyor belts serve, in automobile production, for reception of automobile parts, in particular bodies, in the execution of assembly work and for other production and transport work. The automobile workers working on the automobile parts normally move along with the slowly moving conveyor belt and can move freely on the platform. The individual carrying elements of these assembly lines and/or conveyor belts have wheels or are carried on roller strips. The drive takes place mostly via driven roller batteries which transmit the drive force to the carrying elements by frictional connection. The drive stations are usually arranged at the commencement of a straight conveying section.
Force transmission from carrying element to carrying element takes place on straight conveying sections by means of pushing forces, and at the ends of the conveying sections the carrying elements are braked via a braking station, in order to avoid gaps in the composite pushing structure. Downstream of the braking station, the draw-off stations are usually arranged, which execute a “staggered drawing” of the carrying elements, in order to allow a cross transfer or a vertical transfer, for example by means of a lifter. The rotational movement of the carrying elements usually describes a rectangle. However, other layouts are possible.
The known assembly lines and/or conveyor belts of the type described have various disadvantages. If, for example, the direction of travel of the carrying elements is maintained after the cross transfer, then a 180-degree rotation of the carrying elements is required. The corner transfer necessary for this purpose is a blocked region; that is to say, it is not available for assembly work on the automobile and, furthermore, without a high outlay in terms of protection, constitutes a high risk potential. Corner transfer itself requires a complex sequence of movement with high outlay in control terms, and also the power supply of the platforms presents problems on account of the corner transfer.
Curved carrying elements are also known (DE-A-198 58 989), which, rotating in a closed circuit, form the assembly line and/or conveyor belt, a semicircular curve with a normally constant curve radius following a straight conveying section on both sides. In order to avoid gaps and rifts between the adjacent carrying elements, particularly in the curved sections, the carrying elements have in each case a concave and a convex end face, in each case with an identical radius and center point. The carrying elements can also be operated in an open composite structure. There, too, the drive takes place via stationary roller batteries or via co-moving individual drives.
These curved carrying elements have the disadvantage that, because of the polygon effect of the elongated carrying elements, wide covers which close the rifts between the adjacent carrying elements are required in the curved sections, with the result that the useful area available on the platform in the curve is reduced considerably.
The result of this is that, below a particular curve radius, sometimes the standing area for, for example, an automobile or a body becomes too narrow. In curves with a low ratio of curve radius to length of carrying elements, a considerable polygon effect arises, which, particularly in a closed circuit, leads to a permanent change in the length of rotation. These length changes have to be compensated by means of structural measures; a tangential orientation of the platforms in the arc is not possible in this prior art.